It is prohibited by law to forge special original, such as bills and securities. Thus, image processing apparatuses (copy machines) in which special originals, such as bills and securities, cannot be copied has been proposed in, for example, Japanese Laid Open Patent Applications No.60-229572, No.1-316782 and No.1-316783. In these proposed apparatus, it is determined whether or not an original is a special original forgery of which is prohibited by law, an image of the original determined as the special original is converted into another image, and a paper having the converted image is obtained.
In the above apparatuses, such as copy machines, it is determined whether or not an original is the special original forgery prohibited by law. However, it is difficult to precisely determine whether or not an original is the special original. Thus, it takes a long time to determine whether or not an original is the special original. As a result, a speed at which copies of normal originals are obtained is deteriorated. Further, if normal originals are determined as the special originals in error, the copies of the normal original are not obtained at all. On the other hand, there may be an instance where a special original is not determined as such in error.
In addition, if special originals, such as bills and securities, have been copied and these copies, such as forged bills and forged securities, have been diffused, it is difficult to follow up machines which made these copies based on only information obtained from these copies.
Further, in the conventional copy machine having a unit for preventing special originals from being copied, if the unit is removed from the copy machine, it is possible to copy the special originals.